The development of noradrenergic (NA) and serotonin (5-HT) neurons and projections to cortex will be studied by histochemical, immunocytochemical and biochemical methods. Using an antibody to 5-HT prepared by us, the development of 5-HT neurons will be analyzed in terms of the formation of nuclear groups, cell migration and dendrite growth. The trajectory of 5-HT axons will be analyzed as will the pattern of cortical 5-HT innervation. We will study the phenomenon that triggers growth of 5-HT axon terminals long after the main axons have reached the cortex. The role of 5-HT cells in the morphogenesis of the midbrain will be studied and we shall analyze the interaction between 5-HT and NA axons during regenerative sprouting. Finally, the monoamine innervation of cortex and midbrain in the Reeler mutant mouse will be characterized. We shall attempt to determine whether early formed synapses in Reeler cortex may arise from one of the monoamine cell groups and will study their ultrastructural features.